The SARS Coronavirus Clone and Reagent Core serve and interact with and are integral to the smooth function of each of the projects and cores of the proposal. Aim 1 is to provide a standardized source of SARS-CoV cDNA clones, plasmids, recombinant SARS-CoV proteins, diagnostic reagents, antibodies, platform vaccine candidates (e.g., VRPs, NDV vaccine platforms), molecularly cloned viruses and various SARS-CoV wild type viruses. A centralized source of these reagents is absolutely essential for identifying pathogenic determinants and making valid comparisons among the various SARS vaccine candidates generated during the course of the Program. In this capacity, the Core will continue to produce reagents necessary for successful progression of Projects 1-4 and the animal models core. Aim 2 is to produce molecularly cloned SARS viruses that contain heterologous and ancestral S glycoprotein's (vS), ORF3a (vX3) and ORF6 (vX6) IFN antagonist genes and ORF8 (v8) derived by in vitro reconstruction of published sequences from mainland China and from exotic animal origins. These SARS-CoV-vS isolates will provide us an opportunity to 1) measure and compare cross neutralization titers among the various vaccine candidates, 2) determine if evolution in IFN antagonist genes was associated with increased activity in human cells, 3) examine the role of variant S and IFN antagonist genes in SARS-CoV pathogenesis. Aim 3 is to consult with Projects 1 and 2 and assemble chimeric candidate live virus vaccines that contain multiple attenuating alleles layered throughout the SARS genome. The goal is to create live attenuated SARS virus vaccines that are extremely safe and will defy RNA recombination with circulating coronaviruses in nature. Select candidate live attenuated vaccines with be chemically inactivated. In aim 4, the Core will sequence select molecularly cloned SARS-CoV isolates, revertant and recombinant viruses generated from Projects 1-4 research design. The Core will assist in the identification and confirmation of 2nd site compensatory mutations that enhance in vitro growth with passage. In Aim 5, the Core prepares and maintains candidate VRP and ARRP vaccine strains for use in the various projects. In Aim 6, the Core engages various projects and cores to obtain and produce novel reagents, and to distribute them in quantity and assist in maintaining secure inventories of SARS-CoV reagents and viruses.